Telephone system.



l E. G. WEBSTER.

TELBgmNE SYSTEM. APPLIOATIO FILED MAB. 19, 1909 3 BEEETSTBHEET 1 Patented Sept. 17, 1912.

m n `m J. 9. 9, Vl .NQ

yam E555 H. G. WEBSTER. TELEPHONE SYSTEMi APPLIGATION rILED'MA-R. 19, 1909.

atented Sept. 17, 1912.

3&997;

Mimi55@ WITNESSES H.Y G. ,W ESTER. TBLBPHON `SYSTEM. APPLICATIOIN IILED MAB. 19, 1909.

I MZ@ Patente@ sept. 17,1912. 1

3 SHEETS-SHEET 3.

narran ern'rns ra'rnnr orricn HARRY Gr. WESTER, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS', TO KELLOGG SNITCHBOAED @c SUPPLY COMPANY, A CORPORATION OF ILLINOIS.

TELEPHONE SYSTEM.

amasser.,

Specification of Letters Patent.

Application led March 19, 1909. vSerial No. 484,466.

,to the called line is followed by the applical'tion ot ringing current to actuate the bell of the called party, and such current is ap+ plied either continuously or intermittentlyv until. the called party responds to the call,

whereupon the source ot' ringing current is disconnected from the circuit.

The principal object ot the present invention is to provide a novel arrangement of apparatus and circui s for controlling the application of the ringing current, which shall bc simple, economical to manufacture. and etcient in operation. ln carrying out my in vention, l make use of one or more differential relays and associated ringing keys, or their equivalents, in such control. Thus in one form of the invention, tivo such differential relays are employed, one to connect the ringing source and the other to disconnect it, while in other forms but a single differential relay is employed for this purpose.A l also employ a. novel key construction by which the key is iiorn'ially unlatched and in which the latch "is thrown into operative position upon the connection of the link-circuit to the called line.

vThe invention comprises many novel circuit arrangements which will best be understood upon reference to the accompanying drawings and the following detailed description.

The scope of the invention will be particularly pointed out in the appended claims.

In said drawing, Figure 1 is a diagram of a telephone system having a trunking circuit constructed and arranged according to my invention; Fig. Z is a diagram of a portion of a trunking or cord circuit en'ibodying a modified form ot the invention.: Fig.

3 is a similar diagram of a third -inofflifica-` illustrated in Fig. 1, to a cord-circuit, rather than a trunking circuit. i

In these several views, like parts will he designated by like characters.

4Referring to the drawing in detail and at first more particularly to Fig. 1, A and B designate substation circuits of calling and called lines respectively, which extend by line limbs 1 and 2 to different exchanges, where they terminate in the tip and sleeve jack contacts 3 1, respectively. At one exchange a link-circuit C of Well known con.

struction is employed. In this circuit, the tip and sleeve strands 5 and 6 terminate at the left in tip and sleeve contacts of the answering plug 7, and at the right in tip and sleeve contacts ot the calling plug 8. A trunk, comprising conductors 9, 10, extends between the exchanges. These conductors terminate at their outgoing ends in the tip and sleeve jack contacts 11 and 12 and at their incoming ends in the windings 13, 14, et a repeating coil Whose companion {vindings 15, 16, are connected to the tip and sleeve trunk strands 17, 18 which terminate iii the calling plug 19 adapted to be inserted into a `iack of the called line. It is in association with this latter section oi:` the trunk ,that the novel ringing circuits are associated.

It will be understood that the trunking system here depicted is of the usual type and, in so fa`r as its general arrangement is Concerned, forms no part of my invention.

The circuitI is shown with party lines and station A on the calling line has its circuits shoivniin full, While those at stations A, A2, A3 are merely indicated by the taps ruiming from the line limbs. The called line is similarly provided with stations B, B, B2, B3. Each station is provided with the usual transmitter 20, receiver Q1, switch-hook 9.2, condenserl 23, induction coil 24, and ringer 25. The latter is shown as a` harmonic ringer of the 'type well known in the art. With such ringers, the ringer-s atthe statioiis on cach party line are designed and adjusted to respond to calling currentot certain definite and different frequencies, as is well known. At each substation, a nor iiiallv closed path Jfor ringing current ex tends through the condenser 23, switch-hook aud call-bell 25, and the transmitter Q0 is included in a normally open direct cur- ,relay 27 to the live pole of grounded battery 28. Iiiinb 2 is normally connected to thev opposite, or grounded, pole of Asaid battery through other normal contacts of thel cut-oit relay. Line relay 27 controls the lam 9.9.v

Obviously, in the trunking system thefvbat teries at the different exchanges will belseparate and distinct. n the cord-circuit the Y strands 5, 6 are provided with` the usualv interposed condensers 30, 31, the tip and sleeve Ianswering su ervisory relay-S 32, 33, the calling `tip and s eeve supervisory relays 34,35, the test relay 36, theoperators set 37, the listening key 38-39, and the ringing key ,4Q-415. The relays 32, 33 jointly control the answering supervisory lamp 42,'and relays 34, 35 the calling supervisory lamp 43, while the ringing keyis adapted to connect the ringing generator 44 in circuit, although the latter is not used when the cord-circuit is connected to an outgoing trunk.

At the outgoing end of the trunkv circuit, the sleeve trunk strand 9 is connected to the grounded pole of the battery through impedance coil 45. At the incoming end of the trunk, a trunk relay 46 of high resistance (say, five -thousand ohms) i's included in circuit between the repeating coil windings 13, 14. A condenser 47 is included between the companion windings. 15, 16 and induc tively unites strands 17, 18 of the trunl" circuit. A sleeve relay 48 and a tip relay" 49 are connected to the sleeve and tip strands 18 and 17 respectively. Two differential control relays 50 and 51 control the connections from the ringing generators G, G', G2, G8 to the strands 17 18. The ringing device K coperates in this control and .causes the operation o relay 50 to apply the ringing current. A relay 52, included in these ringing connections, controls the operat-ion of relay 51 to disconnect the ringing source upon the response of the called part-y. '-Interrupters I, I', I2, Pbreak the bridge formed between the 'strands 17, 18, through the generators G, G', G2, G3, at regular intervals, and during such intervals replace` the generator connections by a connection to the positive pole of grounded battery 53. An additional control relay 54 is also included in the circuit. A test relay 55 is normally connected to the tip contact of the calling plug 19 and controls a circuit from battery 56, throughinductionA coil 57 associated with an operators Set 58 and an order wire 59, which extends from the operators at the distant exchange in a manner well known in the art.

It it be assumed that a party at substation A desires to converse with a party at substation B. he willreniove his receiver 2t and thereby energize his line relay 27 to display line lamp 29. The operator willl'respond to the call by inserting answeringplug 7 into learn that connection. is desired with a subscriber whose line terminates VVin the distant exchange, and upon-being assigned a trunk over the order wire 59, will immediately. Ainsert: the calling plug 8 into a jack of that trunk. This act energizes supervisory relay 35 and trunk relay 46.. The circuit by which this is accomplished may be traced from they live pole of battery 28, through this` Winding of relay 35, sleeve strand 6', plu'g and jack Sleeve contactsand'impedalice coll 45 to the return side of .the battery, another path for current extending 'from the sleeve contact of thefjack, through trunk conductora-9, repeating coil winding 14, trunk relay-46, repeat'- ing coil winding 13, trunk yconductor 10,

jack and plug tip contacts, strand 5, and sull pervisory relay 34 to the' return side of the battery. 'By reason of the high resistance of relay 46, current'flovving over this path is insutlicient to y"energize relay 34. Super# visory lamp 43 is thereby energized and remains lighted until, in the subsequent operation, the normallyv open short-circuit about relay 46 is closed. The energization-ot trunk relay 46 will close aI circuit .for guard lamp 60 which may be traced from the live pole of battery 28, through alternate contact 61 of relay 46, and normal contact 62 of sleeve supervisory relay 48 to the return side of the battery. The lighting of this lamp Iguards against improper. connection of the trunk terminals in a manner common in the art. As soon as the operator at Vthe Second exchange has designated the trunk for the first operator to plug into, she at once'tests the line of the called party -by touching the tip contact of plug 19 against contact 4 of the Wanted line, and in case thesame is busy obtains a circuit through test relay 55, which produces the customary click in her receiver as an indication that the line isbusy. In such event, the calling party is so advised through the first operator. finding the line idle, however, the second operator will' insert plug 1.()` into a multiple jack ot' the line running to station B. The establishment ot this connection energizes the sleeve relay 48 and the cut-oil relay 26 of thecalled line over a circuit extending troni the live pole ot battery 28, through re. lay 48, plug and, jack sleeve contacts and relay 26 to the return side of the battery. The operation ot relay 26, as before, completes vthe line limbs to the jack terminals and distest relay and completes a section ofthe tip strand i7 and, by its Contact G2, estab# lishes a ground connection which is instrumental in energizing relays and 51 and 'lighting key lainp (rrand answering lamp The lamp circuits extend from the live ccf pole of battery 28 and. thence, on the one hand, through lamp 641, closed contact GG of 'relay 50, and on the otherA hand, through lamp to conductor 67, Where both branches unite,'thence throughnorinal Contact (S8 of relay 54, conductor 69, through alternate Contact 62 of sleeve relay /l-S to return side ofthe battery. The circuits 'through cont-rol relays 50 and 5l include the, dillierential windings in parallel and, although energizing the windings, do not operate these relays." One path through .relay 5l extends from the live pole of battery 28,.thr.ough the upper Winding of said relay, its closed contact 70, closed contact 71 of relay 52, conductor 69 and alternate contact 62 to ground. The other branch through this re lay extends directly from battery, through the lower 'Winding of said relay, and alten nate cont-act 62 to ground` VThe circuit through relay 50 includes two parallel branches and a common portion. (lne parallel branch extends from the live pole of,y

battery, through tholower Winding of relay 50 to the conductor 72. Theotherbranc'h extends through resistance 7 3, the upper winding of relay 50, its closed contact 74, vto conductor 72. The common portionof the .circuit extends from conductor 72, through closed contact 75 of trunk relay 4G, normal contact 76 of tip relay 49, and thence to `ground through conductor 69 and alternate contact 62. ln the case of relay 5l, the magnetic ellects of the dilferential windings subs antially balance each other; This is also true ot' the differential windings of relay 50, but in the case of the' latter the upper Winding is provided With a relatively larger number of turns than the lower, inasmuch as the current flow through it is cut down by the resistance 73.

The next step in the operation is to apply the ringing current to the called line. The ringing device l includes .keys 7c, rz, k2,

2.23, corresponding to the generators G, G.

G2, G3, and the arrangement is such that if key lc is depressed, current trom generator' G will be applied to the called line and this `current will he of the proper Afrequency to actuate the call-bell at station B. rl`here is n similarcorrespondence between keys Zi. 7a2. Z13 and stat-ions B, B2, B5, respectively. Thus; under the assumption that the party at A desires to converse Witha part-y at ll, the operator Will depress ringing hey Ic and thereby connect the generator in bridge of ther strands 17, 18. The key K is so con- '.51, to strand 18.

structed that when the plunger is de-v pressed all the Way te its ringing position, the contacts 80, Sl are closed and the bar 7 7 is moved dowim'ard to close the contact springs 79, 'the plunger .7; then returning to its indicating position being heldthere by the vpin in 'the' bar 7 7, and the bar 77 returning upward allows the contact 79 to again open. Thus, it will be seen that the Contact 79 is closed only when the plunger'. radeln-esseri to its rii'iging position. The depression of the key 7i to its ringing position causes the sliding-bar 77 to more downward through` its guides 78 to close normally open contact, 79, thereby` short-circuiting the upper Winding oi relay 50 and causing said relay to pull up its contacts. T he opening ol contact G6 puts out the key lanipft, thus showing that ringing current has been applied. rlhe opening ci? contactHl.4 permanently opens 4the branch through the upper Winding ot relay 50 and thus leaves said relay locked through its loW-erwinding and the alternate contact ot the sleeye relay 4S. The movement oli the key la also closes its contacts ql, thus'couipleting the ringing bridge above referred to. rlhis bridge may be traced from vstrand 17, through normal Contact 82 of. relay 5l, closed Contact', 83 of relay 50, relay 52, closed contacts H81, interruptor l, generator G, closed contact 84 of relay 50, and normal contact 85 of relay terval, the remaining portion ofthe circuit includes the limbs of the called line and theA callbell 25, switch-hook 2Q, and condenser 23 at substation B. Thus While interrupter l is in position to include the generator G in circuit, the call-bell 25 is actuated. In response to the ringingol" his call-bell. the

called party 'will remove his receiver from its hook and thereby coin plete a conductive bridge between the line limbs at his substa tion. This act will close a Acircuit through relay 52, closed contacts 83, SZ'tothe tip side of the circuit, thence out over the line through the substation and back over the sleeve side ot the circuit, and relay 52 is thereby operated.- lts operation `ivill open the path through the upper irinding'of relay 51 and dost-roy the balance'. in that relay and thus actuate to interrupt the ring ing bridge at contacts S2.' 85,and complete the'strands 17, 18v of the trunk circuit. As soon as the tip strand is thus completed, cur- During the ringmg invrent will flow through the tip'rclayi 49, and

the locking circuit through the lowerwindlug of relayO `willf'he interrupted at contact 76, thereby allowirlg said relay to return tc its normal position. The actuation ol contact 7 (i will thereupon complete a circuit 'for relay V54 through conductor 69 and alternate 4a locking circuit for itself through alternate y' contact 68, conductor 69, and alternate contact 62 'of relay 48. The closing of contact '86 of relay 49 will short-circuit tl` trunk visory relays 48 and 49, and upon the fleenergization of the former at the end of conversation, will display the lamp as a signal for disconnection. v'Ihe sho-rt-circuitinof 4trunk relay 46 upon vthe energization o tip relay 49 causes sutlicient current, to flow through tip relay 34- associated with the cord-circuit to energize that relay to eXtin guish supervisory'lamp 43, thus indicating to the first operator that the connection has been completed through to the called line and that the called party has responded. At

.the end of conversation, the restoration of the calling partys receiver displays super visory signal 42, while the restoration of the called partys -receiver 'denergizes tip v relay 49 opening the contact 86 and allowthe calling party will be notified of the busyv ing the rle'lay 46 to again energize over the previously traced path, from the cord circuit C. The relay 34 is now denergized due tothe cutting' in of thev high resistance vvwinding of relay 46,'lighting the disconnect signal 443 ofthe cord circuit C. -The operator now observing the two signals 42 and 43, disconnects 'the plug 8 vfrom the jack,

' thereby again openingthe circuit for the relay 46 which now denergizes. A circuitfor the trunk disconnect lamp 60 is now closed from battery 28, through th'e lsaid lamp 60, normal contact 61, normal Contact' 76 of relay 49 to ground at 'alternate contact 62 of relay 48. TheA operator now withdraws The removal no'rmal'position. The key k, having been depressed, remains 1n this condition until one'of the other keys k', le?, la is operated,

.Y whereupon the movement of the sliding-bar 77 releases key cand allows it to return to normal. V

In Fig. 2, I have illustrated' theright- -hand portion of either a trunk-circuitor a cord-circuit which is' provided with a modified circuit arrangement employing a differential relay for controlling the connections fromthe ringing generators. instancefth'c ringing device K is ot the, same construction as that of Fig. 1 and controls a similar contact `79 which in this instance, however, is normallyV closed. It likewise controls the connection oit the generators G, G', G2, G3 to the strand 17. In this instance, however, the interrupters I, I,I2, I3, and the battery 53 of Fig. 1 are omitted and in lieu thereof a flip flop relay 87 is In this ent-iai control relay 89. The tip relay 49 is y I .here provided with normally open contacts 9() 91, which include-'the strands 17, 18. A key lamp 92 and a supervisory lamp 93 are also provided. In this instance, the sleeve relay 48, b its contact 63, normally includes the test reay 55 in circuit with the tip con` tact of the plug 19 and completes this portion of the strand 17 upon the energization of the relay, as in the case of Fig. 1. The

contact 62 of relay 48 provides circuits for the lamps 92, 93; the former extending from the live Apole of battery 28, through lamp 92, contact 94 of relay 89, normal conta-ct 95 of relay 96, conductor 97 and closed contact 62 tothe return side of the battery; and the latter from the live pole of the same battery, through lamp '93, normal Contact' 98 of relay 49, conductor `97 and closed contact 62 to ground. IRelay 89 has its two windings energized over the sleeve side of the circuit, through the cut-oil relay of the called line. In operation, if it be assumed that the operatorV has learned the number of the called line, she will test in the usual way and condition of the line, or she will insert the plug 19 vinto the jack of the called line, as

in the case of Fig 1. This latter act will actuate Vrelay 48 over a circuit including the cut-off relay of the called line. The test-relay will thereupon be disconnected and the strand 17 closedY at alternate contact A63.

`.The closing of contact 62'will light lamps 92, 93 over the paths previously traced. The

act of plugging in. in addition to energizing sleeve relay 48, will energize the windings of differential control relay 89, butwithoutcausing its actuation. The circuit. through .the lower winding extends from the live pole of battery 28, through said winding, condctor 99. normal contact 91 of relay 49, sleeve strand 18. plu, r and jack sleeve contacts, through the winding of the cut-oit' relay of the called line. tothe return side of the battery. The circuit through the upper winding of relay 89 will extend from the live pole of the battery through said winding, closed contact lOOfof said relay, closed contact 79 of the key, thence via conductor 99 and sleeve strand 18, through the cut-0H relay to ground, as in the case of the lower winding.' Ringing current will be applied by depressing one of the keys c, la. k2, ,n3 as before, .according to the party to be called. It' it be assumed that key It' is depresseththe sliding-bar 77 will open Contact 79 and thereby destroy thebalance in the windings of relay 89 and energize said relay to attract its armature.

This will result in the permanent opening of contact 100 and the continued energization of said relay over the sleeve side ot' the circuit and through the cut-oli' relay. The depressing vot key la Will. also close its contactsI 80, 81,' toconnect the grounded generator Gr to conductor 101 which is adapted to be intermittently connected to tip strand 17 by contact 102 ot tlip liep relay 87.. A circuit 'is completed through this .latter relayand the interrupter it upon the actuation ot' relay 89. The action of the interrupter will intermittently energine relay Si", and during 'such energized condition,conductor 101 Will be connected to tip strand i 7 and ringing current will be proiecied out over the tip side ot the called line, bach over the sleeve side to ground, through the cut-ofi relay and the relay 89 and the circuit of battery 2S. Thus the called partys bell will be. intermittently rung. Jpon. his response, he will close a conductive bridge at lhis substation, and then, as soon relay S7 is denergized, a path for current will extend from the live pole of battery 28, through sleeve relay 48, and thence to ground through the cut-oli' relay ot the called line, and inV parallel with the path to ground through the .cut-oit1 relay, out over thek line, through the subscribers station, and back over the tip side ot the circuit, through the tip relay 4:9 to Ithe vreturn side of the battery. As soon as tip relay 49 is thus energized, relay 89 will be denergized by reason. of the opening of its circuit at contact 91, and thus the flip flop relay Will be denergized, leaving the vstrand 17 closed at alternate Contact 102.. The same strand Will be closed at contact 90 otV tip relay L19, while strand 18 will be similarly closed at alternate contact 91. Contact 98.0f tip supervisory relay 4:9 will interrupt the circuitot supervisory lamp 93 to cause its extinguishinent and will connect relay G to ground through conductor 97 and closed contact (-355 'ot' sleeve relay 48. The energization of .relay 90 will open-the oriffinal circuit through vlamp u2 at its contact 95, thereby preventing the illumination of such lamp upon the denergizationof control relay 89, it being noted that the lamp 92 was extinguished upon the enerrgl'ation of the latter relay'. lilith the circuit in this condition, conv tion 'may be carried on. `At the end ot ionversation, the restoration of the called 'partys receiver denergizes tip supervisory relay flu and thereby lights lamp i 93 as a disconnect signal` The connection 5,5 will then be taken down in the usual Way. in the 'form et the 'invention illustrated in Fig. a iird arrangement circuits and a slightly dilierent key device is illustrated. .ln thiQ tie'ure. the #eine portion ot an intervenu'. t1 9; link-circuit is shown.

in Fig. and.' as uther the end or a .nections as betere tension ot' the spi-ino' 106 until its circuit. "Here the ands 17, 1S extend through ntuinallj.' open contacts oit fliilferenl tial control relay 1023, to the' calling plug 10, l

tip strand 1'7" being also normally interrupted at. contact 6B of sleeve supervisory relay 13. l test relay with the saine 'conemployee. A relay 52", similari() the relay 52 of Fig. l, is located in thc ringing coniieetione.y ln addi tion, a tip Supervisory relay l0 and a locking` 1'" guet 1.0i ttor the ringing device l are provitlcd. ln this inetauce, the control relay 10B has its windings differentially energized by a circuit which extends tluough closed contact G2 oit relay tu to ground, instead of through the sleeve side of the c'irci-.itas in lfi il. in the ringing device lic, the heys l hlt", 7a2, .View are norinully and cannot be looked until inagnet 10-.lis actuated. The armature 105 of this inagnet is ynovided with a spring 106 which engages the end oi14 the locking bar 10.7. 1illhen magnet 10i energized, bar 10in moved throughil guides' 1.08 so as to bring its catch projections 109 into position to engage the pine 110 on the keys. By reason ot' the yielding connection between the bar l07'aud the armature. 105. the depression of a key forces the har 10i" back against the Y, pin 110 has passed beyond the cooperating projec tion 100, whereupon the har springs ybach into position and holds the key depressed. lln this instance, the contacts U14-112, 113)c 114-, connect the genrators G, G', G2, G3 with their interrupters l, l, l2, lr' in circuit. Consideril'ig the operation and assuming that the operator has tested. the called line and found it idle, the insertion of plug 19 into a jack ot the called line will actuate sleeve supervisory relay i8 in the usual Way over the sleeve side ot the circuit and through the cut-oli relay. This will close tip strand 17 at alternate contacts and will light supervisory lamp 115 over a .path extending troni ihelive pole of battery 28, through lamp 115, closed contact 1.1(3, and closed Contact. 11.7 to the return side oif the battery.' At the same time, the loclziu magnet.- lOel (vill. he included in parallel iv the .lamp 11.5 and thereby eue-M the locking bar 10T into incl ng The closing of Contact (Si), ol" relay also energien both wiudif c relay 1.0% without causing its actua rThe path the lovverwint 'un' tzl-.us eet from the live prille oi.' battery f .i eaid winding, and closed co tact ground. 'lh-c path through the other wind-- extentie .trom the live `mile. oi' 'the saine threw-'fh said winding, closed coubattery, tact 11S of said relay, closed contact itil oit :les

relay 52', andas licitar. through closed 13a Contact G2 l'o groiiuei. lilith the par 1 this cruiditicn, he operator will tlc-ier;

et the heya afi llo, a ul llu'zrel.

generator G- 'with the. init-.rtw

oi the strano, il", itl, l h the noi'r 19,-*

:mal contacts 120 generator dition of the circuit.

out over the called line and through the calledvstat-ion. During thenon-ringing in-' tervahthel tip side of the circuit will be connectel' 'to ggound through the direct current turn Side' fof sleevevrelay 48 and battery 28". As soo-nl as sthe V:called party Yremoves his receiver from its' A"heck flow throughrelay 52, out over the called line, through the substation, back over the sleevefside of thfe circuit; 52 will be actuated tointerrupt the branch through the uppenwinding of relay 103,

thereby destroying the balance in its Wind-` ings and causing 1t to interrupt that branch permanently at its contact 118 and t0,.d1s connect the ringing bridge at normal contacts 120, 121, and complete the link-circuit strands 17, 1S at alternate contacts 120, 121'. The resulting closure of the tip strand 17 will provide a path for current from battery 28, `through sleeve relay 48 and out over the sleeve side of the circuit to ground through the cut-od relay the tip side of the circuit and through tip relay 49. The resulting energization of relay 49 Will' interrupt the circuit of lamp 115 and locking-relay 104, thereby indicating the completion of the connection to the operator and Jfreeing the key o. parts in this condition, conversation may be carried on. At the termination of conversation, the restoration of the called pa-rtys.

receiver will interrupt the path for current through tip relay 49 energization will light asV an indication to the supervisory lamp 115 operator of the conl Upon taking down the connection, the parts will be restored to normal.

In Fig. 4 I have shown the ringingcircuits of Fig. 1 applied to a cord-circuit instead of a trunk-circuit, asin the latter gure. In such instance, the circuit through Contact ofthe trunk relay 46 extends through normally open contacts of answer? mg supervisory relay 32. In this figure, I have also illustrated a ringing device K, which provides for the same operation as the ringing device K in Fig. l and is provided, in addition, with the locking bar conringing device KO of Fig. 3. InI this instance also, the operators set 37 and test relay 36 are' located at the answering the ringing key 1s provided with an addi tional contact 122 by which the test relay 36 is brought into circuit with thev tip contact and of relay 103, th'ere5 "by intermittently' projecting ringing current' The opposite side of vthe cir- 'cuit will be connected to ground, or the re-' this generator, through' the; cnt-ofi' relayof the called line and through' and thereby conductively unitesy "the-limbs of his telephone line, current will As a result, relay the o eration of the trunking circuit of Fi l' therefore need not be set ,out at this point. It Will sutiice to point out that the actu tion of relay 48, upon being plugged into the called line, will complete a circuit for locking magnet 104 through closed contact 123 of relay 52 and contact 62 of 'relay`48. lThis Will operate magnet l104 to bring the latch-bar 107 into operative position. Upon the response of the called party, the energization of relay v52 cuitv at contact 1,23 the ringing device The bar 107 is provided with the tions 109 like the bar 107 of Fig. 3 and these and allowthe parts of K to return to normal.

projec- Will interrupt this cirthat case. In addition, it is provided with slots 124 which coperate With the pins-110,'

upon the complete downwardmovement of the keys 761, 1, k12, la to close the normallyv open Contact 79 tovactuate ldifferential vcon` x and to ground over y With the and its resulting de,

.end of the link-circuit and.

trol relay 50, as explained in connection with Fig. 1. Th

responds to the normally open contact 75 'of the trunk cuit through `,lay 50.

In carrying out my invention, it Will be apparent that many alterations and-modilications may be made in the circuit arrangements. and in` the apparatus employed in those circuits without departing from the spirit and scope of my invention. Thus in many instances, theseveral batteries Vmay be one and the same, the contacts for applying ringing current may be operated by other devices than the ringing K0, K', and other changes may be made. I therefore do not wish to be limited to the specilic matter herein disclosed,'but aim to cover by the terms of the appended claims all such alterations and modifications.

1. A telephone system comprising a telephone line, a link-circuit for connecting with said line, control relays, connections from said Source through normally Aopen contacts of one of said relays, means dependent upon the conthe windings of control re- 'nection of said link-circuit to said line to `operate said relay to connect said source to said line, means controlled over the line circuit to yoperate said second relay to directly disconnect said ringing source,A and means responsiveto such first relay to normal.

2. A telephone system comprising a telephone line, a link-circuit for connecting with said line having tip and sleeve strands, tip

9e e normally open Contact 125 of' the tip supervisory relay Aof this figure cor.

relay 46 in the control of the cir- 1 0 5 devices K,

a source of ringing current, twol operation to restoresaid both relays diiierentially, .inea

Losses? lnys,'connections from said source Ythrough normally open contacts of one ot seid relays,

ine-uns for actuating smid control relay byclosingr a circuit through contacts of# said tip and sleeve relays to connect seid source to scid. line, and menus for actuating the sec oud control relay to disconnect sind source by a circuit through contacts of said tip relay.

3. A telephone system comprising e. Jelephcne line7 u link-circuit for connecting With said line having tip and sleeve strands, tipy and sleeve relays connected with said strands, a source of ringing current.y two control relays, contact-s for closing nn actuating circuit for the first control relay through contacts of seid sleeve relay, to connect seid source to said line, and contacts Jfor changing the second control relay connections to Actuate it to disconnect said source b f a circuit throuvh contacts of said f sleeve relay.

el. A telephone system comprising a telephone line7 a linkrircuit for establishing connection to said line. a source of ringing current, two differential'control rilnys, normally open connections from seid source to said line through contacts of .relays7 means lor energizing said windings of both relays differentially, means for subsequently destroying the dilierential action of the 'windings of one of said relays to apply ringing current to the line7 and means for subsequently destroying the dilferentinl action oit the windings of said other relay to disconnect said source from said line.

A telephone system comprising a telephone line, a linkcircuit vtor establishing connection 'to said line, :i source of ringing;` current, two diii'erential cont-rol rel ays, normally open connections from seid source to said line tln'cugh contacts oit one of said relays, means for energizing said windings of s ior @pew ing` the circuit one dill'ei lul Winding of said relay to apply ringing; current io seid line, and 'means tor sul'isequently open insg the circuit of one d licrential winding' oi the other ot' seid relays to disconnect suini source :troni said l. fi. telephone Yein rouujiri telephone line, u. li'nn circuit for establishing connection to seid line. two tillcrential control relays? n( '.ally open connections from said source to said line tlirough contents olf said relays means dependent unen the connection olf said 'i V.ii-cuit to en ergizice scifi .vinmn relays ilcr entinlly. a differential a oit seid relays i .said line. and switch in brio 2s or one Vurrent to the limbs of suifl line for subsequently opening a cir 65 cuit to destroy the. diil'ei ntie-l' action of the windings of the other ci:1 said relays to discennectseid source troni seid line.

7. 'A telephone system comprising a telephone line.' u linlccircuit for establishing 'connectimi to said line7 two dinerential control relays, normally open connection' 'i sind source to said line through contacts of suid relays, ineens dependent upon the connection of said line and linlccircuit to energize said windings ol both relays dil'lerenliiully, a ringing device for short-circuiting c diterential Winding of one of .snicl relays to apply ringing current to seid line, third relay having contacts included in the energizing circuit of e differential winding of the other of said rliierentisl 1"elays,'and a switch in bridge oi the liinhs oi' snif-l line for subsequently closing a circuit through said third relay to operate the second dit lerential relay to disconnect seid source from said line. A

8. A telephone systein comprising a tele phone line, a linkcircuit. for establishing connection to said line, two dilierential control relays, normally open connections from said source to said line through contacts of said relays, ineens dependent upon the connections of said line und .link-circuit to energize said windings of both relays difierentinlly, a ringing device for shorten-cuitiuga differential Winding of one of said relays to operateit to apply ringing current to said line, contact-s actuated thereby to interrupt the circuit of said winding, n tiircl relay having contacts included in the energizing circuit ol diii'erential Windingl i he other of said dilerei nl 'and n. switch in bridge of the lnnbs of esiti line for subsequently closing a circuit- 'through seid third relay to operate the second difleren'tial l to disconnect said source 'from s l line.

L "elephone system cinnprising a 'telefl phone line. link-circuit for estuhlisl lng' 'i 'Y to said lin a source oi rinn.

..7 two f jlill'erential ci' ly open connections from line iliirougli contri nergriziug su lilly, a

u diileren.

.i id line, ContactV5 lic :n to interrupt the circuit i'or y 'lestroying tl v'iulings oi' snit.

i son; 'e itroni sirio. l' qilioncsyslciu cs Vin; i ,7125 phone liiu.. i l ccnneclion 'lo current, 'tv-sc I mally open connections from said source to short-circuiting a differential said line through contacts of said relays, means for energizing the windings of both relays differentially, a 'ringing device"for short-circuiting a differential winding 0f one of said relays to operate it to apply ringing current to said line, contacts actuated by such operation to interrupt the cir-` cuit' of such' short-circuited winding, means for subsequently opening the circuit of one winding of the other of said relays to operate itto disconnect said source from said line.

1l. In a telephone system, the combination of two diiterential control relays, a connection extending through normally open contacts of the first of said relays and normally? closed contacts of the second, means for energizing the windings of both relays differentially, a switch forv subsequently short-circuiting a differential winding of the first relay to operate it to close said' normally open contacts, other contacts actuated by such operation to open the circuit of said shin-t-circuited winding, and switch contacts for subsequently destroying the differential action of the windings -of said second relay to open said normally closed contacts.

12. In a telephone system, the combination of two differential control relays, a connection extending through normally open contacts of the first of said relays and normally closed contacts of the second, mea-ns for energizing the windings of both relays differentially, a switch for subsequently winding ot' the first relay to operate it to close said normally open contacts,l other contacts actuated by such operation to open the circuit of said shortcircuited winding, and switch contacts for subsequently interrupt ing a differential winding of said second relay to actuate it to open said normally closed contacts.

13. .In a telephone system, the combination of two differential control relays. a connection extending through normally open contacts of the first of said relays and normally' closed contacts ot the second, ineans for energizing the windings of' both relays differentially, a switch for subsequently short-circuiting a differential winding of the first. relay to operate it to close said normally open contacts, other contacts actuated by such olieration to open the. circuit of said short-circuitcd winding, switch contacts for subsequently interrupting` a differential winding of. said second relay to actuate it to open said normally closed con tacts, and other contacts actuated by.V such operation of said second relay .to interrupt `the circuit of its said differential winding it another point.

1,4. Ina telephone system, the combination of two differential control relays, a conjnection extending through normally open contacts of therst of said relays and normally closed contacts .of the second, ,means for energizing the windings of both ,of said relays ditterentially, contacts' for interruptingthecircuit of a differential winding of the first relay to operate it to close-said normally open contacts, and contacts for subsequently interrupting the circuit of a differential winding of the second relay to. y operate it to open said normally closed con-` tacts. 15. A telephone system comprising a telephone line, a link-circuit for establishing connection to-said line having normally open talking strands, asource of ringingcurrent, two relays for controlling the continuity of said strands and the application of ringing current to the line, means forf operating the first of said relays to apply ringing current to the line, means for subsequently operating the second relay to disconnect said ringing source and complete the normally opentalking strands, and means responsive to such operation of' the second relay to restore the fiistrelay to no1'-v mal.

16. A-telephone system comprising a telephone line, a link-circuit for establishing connection to said line, a source of ringing current, two differential control relays, a connection from said source to said line through normally open contacts of the first relay and normally closed contacts of the second, normally opencontacts for the sec ond relay included in the talking strands .ot said link-circuit, means dependent upon the connectionY of' said link-circuit to said line to energize the windings oflboth relays differentially, means for subsequent-ly destroying the diiterential action of the windings ofl the first relay to apply ringing current to the line, and means for subsequent-ly destro-ying the differential action of the windings of the second relay to disconnect said source and complete the talking strands at said normally open contacts.

' 17. A telephone system comprising a tele-- phone line, a link-circuit for establishing connection to said line,'a source of ringing current, two ditlerential control relays, a connection from said source through normally open contacts of the first relay and normally closed contacts of the second, norl mally open contacts for the second relay included in the talking strands of said linkcircuit, means dependent upon the connection of' said link-circuit. tosaid line to enervgize the'windings of both relays differentially, a ringing device for subsequently interrupting the circuit of one differential winding of the first relay to apply ringing current to the line, and means for subselink-circuit, a

' tially, a ringing will connection to said line, a source of ringing current, two differential control relays, a connection from said ysource through norinally open contacts of the irst relay and normally closed contacts of the second, normally open contacts for the second relay included in the talking strands of said linkcircuit, means dependent upon the connection of said link-circuit to said line to energize the windings of both relays diiierendevice for subsequently interrupting the circuit of oneffv'dierential winding of the first relay to apply ringing current to the line, and a switch associate with said line and suitable connections for lsubsequently interrupting the circuit of one differential winding of the 'second relay to disconnect saidsource and' complete the talking strands at said normally open lcontacts.

19. A telephone system comprising a calling telephone line, a called telephone line, a link-circuit included incircuit between said lines, a source of ringing current, two control relaysconnections from said source to the called line including normally open contacts of the iirst relay and normally closed cont-acts of the second, means for operating the first relay and locking it in actuated position to apply ringing current to the called line, means controlled over the answering 'end of the link-circuit to operate said second relay to disconnect said ringing source, and means controlled over the calling end of the link-circuit for restoring said first relay to normal to disconnect said source.

20. VA telephone system comprising a calling telephone line, a called telephone line, a link-circuit included in circuit between said lines, a source of ringing current, two control relays, connections from said source to the called'line through normally open contacts of the first relay and normally closed contacts of the second relay, contacts and connections for operating said iirst relay to ringing current to the called line, -a thir relay and connections for operating said first relay to disconnect said source, a control circuit for said 'third relay includingl conductors of the answering end of s-ai for operating said second relay to disconnect said source, anda control circuit for said fourth relay including conductors of I the calling end -ofsaidllink-circuit.

21. In a telephone system,

rent, a relay for controlling a circuit from current and ringingl phone-line, a fourth relay and connectionsy a source of cursaid source having two energizing windings, a circuit including two parallel branches, one including one winding and the other including the second winding and normally closed contacts of said relay, means for closing said circuit to energize said windings differentially, a normally open short-circuiting branch about said second winding and normally closed contacts, means for closing said short-circuiting branch to actuate said relay, whereby the branch through said second winding is broken at said normally closed contacts.

22. A telephone system comprising a telephone line, a ylink-circuit for establishing connection to said line, a relay operated upon the establishment of such connection, two diderential control relays differentially energized by the operation of said relay, a source of ringing current, connections from said source to the connected line controlledv by said ditierential relays, means for operating one of said differential nect said source to said line, and means for subsequently operating the other differential relay to disconnect said source 'from said ine.

23. A telephone system comprising a telephone'. line, a link-circuit for establishing connection to said line, a relay operated upon establishing such connection, a didierential control relay and connections for energizing its windings differentially upon the operation of said first relay, a source of ringing current and ringing connections therefrom through normally closed contacts of said diiierei'itial relay, other contacts for closing said ringing connections to apply ringing current to said line, ,anda relay for destroying the diierential action of the windings of said diiierential relay to disconnect said source -from. said line.

24. A telephone system com rising a telephone line, a link-circuit ifo connection with Isaid line, a differential control relay and connections for energizing its windings diiierentially upon the establishment of such connection, a source of ringing connections through normally closed contacts of said relay, other contacts for closing said ringing connections to apply ringing current to said line, and a relay for destroying the differential action of the windings of said relay to disconnect said source from said line. Y

v25. A telephone system comprising a telelink-circuit for establishing connection with said line, a diiierential control relay and connections for energizing its windings diii'erentially dependent upon the establishment of such connection, a source of ringing current and' ringing connections relays to conestablishing izo through normally closed contacts of said relay, other contacts for closing said ringing l mento 'connection with said line,

phone line, 2 0

action of 'the windings-.of said relay to dis-v connect; said source from said line, and a switch associated with said line and operative to close a circuit to operate said lastmentioned relay.

26. A telephone system comprisinga telephone line, a link-circuit for establishing a differential control relay and connections for energizing its windings diiferentially upon establishing such connection, a source of ringing current and ringingconnections including contacts of said relay, and means for operating said.

re1ay by opening the circuit of one of saidf g relay, whereby the operation of said second windings. l

27. A telephone system comprising a telea link-circ connection to said line, '.a differential control relay and connections for energizing its windings for destroying the bal'anceinsaid diii'erential other winding of said relay to disconnect said source 'from said line.

28. A telephone system comprising a telephone line, a link-circuitfor establishing connection with said line, a differential control relay windin differentially upon the establish. ment ouch connection, a source of ringing current, ringing connections including normally closed contacts of said relay, other 40 ,contacts for closing said ringlng connections 'to connect said source in circuit. with said line, and contacts for destroying the balancev in said windings to operate said relay to disconnect said'source from said line.

' 29. A telephone system comprising a telephone line,a link-circuit for establishing connection with said line, a differential control relay and connections for energizing its windings-differentially upon the establishment o normally open contacts included in the talking strands of said link-circuit, a source of ringing current, ringing connections including normally closed contacts in said relay, other contacts and connections for including said source in circuit with said line to apply ringing current thereto, and contacts for destroying the balance in said windings to operate said relay to disconnect said source and complete said talking strands.

connection with said line,

uit for establishing.

diii'erentially uponv the establishsuch connection, a source of ringing current, ringing connections including nor- I mally open contacts of said relay, contacts' and connections for energizing its such connection, said relay having windings differentially upon theestablishment of such connectionfa source of ringing current, ringing connections from said source to said line through normally closed contacts other4 contacts for closing said i ,l

of said relay, ringing connections to connect said source in circuit with said line, a second relay in said ringing circuit, means for rendering said second relay unresponsive to ringing current and responsive to direct current, a source of direct current, a circuit including said latter source, second relay and line, a switch for closing said last circuit to energize said second relay, and contacts on said second relay and connections for destroying the balance in the windings of said differential relay operates said differential relay to dis- -connect said ringing current source from said` line. t A

3l. Altelephon'e system comprisin a telephone line, a link-circuit for esta lishing connection with said line, a differential control relay and connections for energizing its windings differentially upon the establish- 'ment of such connection, said relay having normally open contacts included in the talk-L ing strands of said link-circuit, a source of rlnging current, rlnging connections fromy said source -to said line through normally closed contacts of said relay, other contacts for closing said ringing connections to connect said source in circuit with said line, a second relay in said ringing circuit, means for rendering said second relay unresponsive to ringing current and responsive to direct current, a source of direct current, a circuit including said latter source, second relay and line, a switch for closing said last circuit to energize said second relay, and contacts on said second relay and connections for destroying t'h'e balance in the windings of said differential relay, whereby said differential relay is operated ,to disconnect said ringing current source from said line and complete said talking strands. I

32. A telephone'system comprising a telephone line, a link circuit for connecting with said line, a source of ringing current, two 'control relays, connections from said source through normally open contacts of one of vsaid relays, means dependent upon the connection of said link circuit to said line to operatesaid relay to connect said' source to said llne, electromagnetlc means controlled by current over the, llne circuit to operate said second relay to directly disconj nect said ringingsou'rc'e, and means responsive to such operation to restore said first relay to normal. f

33. A telephone system comprising a telephone line, a link circuit for connecting with said line, a source of ringi'g current, a controlrelay, connections from saidv source through normally open contacts of said conresponsive to such operation to restore said trol relay, means dependent upon the -concontrol relay to normal. 10 necton of said link circuit to said line lo In Witness whereof, I hereunto subscribe operate said control relay to connect said my'narne this 17th-day of March, 1909.

source to' said line, a disconnect relay, a vHARRY Gr. WEBSTER. source of direct current controlled over the Vitnesses:

line circuit to operate said disconnect relay CAROLYN WEBER,

tou disconnect said ringing source, :ind mea-ns A. H. DYSON. 

